Overhead they could see the shadowy form of the broken beam still hanging, and still threatening to fall at any moment. The rope fastened to it had broken below the point where they were seated, and was within reach of their hands; but it was of no use. Had the beam above been strong, they could have easily saved themselves in this way; but the beam being broken, they dared not touch the rope. The terror of the broken beam was, however, lost sight of in the presence of that greater terror advancing from below, minute by minute--the terror of that water into whose mysterious sources they had penetrated; whose secret fountain they had broken up, and which now, like some formidable monster too rashly challenged, was advancing step by step, in irresistible power, to take vengeance upon these reckless intruders. That soil beneath had shown its looseness by tumbling down in the removal of the lower logs; the tenacious upper clay did not exist there; and it seemed to them that the rising water, by permeating all the soil, might at any moment cause all the pit to fail together in one heap of undistinguishable ruin. In that case, they would be overwhelmed beyond the possibility of escape, and snatched from the world to destruction, without leaving behind them the faintest vestige, or the slightest token of their awful fate. At such a moment nothing was said. Nothing could be said. They sat there then in silence, listening with sharpened senses for any sound that might tell of the approach of the water. For a long time, however, they heard nothing except the quick throbbing of their own hearts, until, at last, there gradually came up a dull sound, which slowly resolved itself into something like thumping and grinding. They listened now with intense excitement and agitation to these sounds. What were they? There was only one meaning which they were able to give to them. It seemed as if these sounds must indicate the breaking up of the lower casing of logs that lined the pit--the first notice sent them of that break-up which was inevitable. Every sound seemed to tell of some new log severed from its place by the pressure of the surrounding soil, which, now saturated with water, and transformed to a sort of ooze, streamed through the crannies, and destroyed the staying of the pit. At this thought the expectation of the end grew stronger, their awful doom seemed more immediate, and every nerve tingled, and every fibre of their being thrilled with a sense of horror.